Base plate for a drug pump

ABSTRACT

The present invention concerns a pump provided with a control module and an attachable fluid reservoir cassette. The control module includes a pumping mechanism for pumping fluid from the fluid reservoir to the patient. The cassette is provided with appropriate indicia to identify differences between a plurality of cassettes. The control module further includes cassette indicia identification structure for identifying indicia on the cassette. One type of cassette identification system includes a projection extending from the cassette and structure associated with the control module which engages the projection. Another type of cassette identification system includes a light reflecting system which utilizes light from the control module and reflected off the cassette. Still other types of cassette identification systems utilize other non-contact switches or sensors to sense indicia on the cassette to identify the cassette from a plurality of cassettes.

This is a continuation of application Ser. No. 08/228,508, filed Apr.15, 1994, now U.S. Pat. No. 5,531,697 which application is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates generally to drug pumps for pumping fluidto a patient. More particularly, the present invention relates tosystems and methods for identifying attachable fluid cassettes whichsupply fluid to the drug pump for pumping to the patient.

BACKGROUND OF THE INVENTION

Various drug pumps are known for pumping fluid to a patient inconnection with treatment of various medical conditions. Drug pumps areknown which include a reusable control module with a disposable orreusable fluid reservoir cassette wherein the reservoir is eitherself-contained with the cassette or remote from the cassette. Thecontrol module pumps fluid from the cassette to the patient when thecassette is attached or mounted to the control module.

There is a need for using the control module in connection withdifferent fluid reservoir cassettes. The cassettes may differ in thenature of the drugs or other fluid contained therein. Other differencesmight relate to the manner in which the fluid reservoir componentcooperates with the control module to deliver the fluid to the patient.For example, the control module may include a pumping mechanism whichengages a tube extending from the fluid reservoir cassette. The fluidreservoir cassettes may have variations in tubing size. In that case, itis important to identify to the control module the size of the tubingattached to the fluid reservoir cassette so that the proper amount ofdrug is delivered to the patient.

There is also a need for identifying a proper cassette from an impropercassette mounted to the control module. In some cases, the controlmodule may be programmed or configured to pump fluid in a certaintherapy from a particular cassette. If an improper cassette is mountedto the control module, there is a danger the patient may be given animproper drug.

There has arisen a need for systems and methods for identifying a fluidreservoir cassette which mounts to a control module of a drug pump.

SUMMARY OF THE INVENTION

The present invention relates to a pump including a control modulehaving a control system with a processor and associated memory forcontrolling operation of the pump. The control system also includes apumping mechanism for pumping fluid which is controlled by theprocessor. A fluid reservoir or cassette is selectively mountable to thecontrol module. The fluid reservoir includes indicia for identifying aproperty of the fluid cassette such as tube size, drug type, or other.The control system includes structure for identifying the indiciaassociated with the fluid cassette. The structure for identifyingindicia sends a signal to the processor indicative of the indiciasensed. An appropriate signal is generated for controlling the pumpingmechanism or other pump function based upon the indicia identified. Ifan improper cassette is sensed, then a pump disabling program disablesthe pump mechanism from pumping even though the operator attempts toinitiate the pumping operation.

In one preferred embodiment, the reservoir includes a base plate and atube extending from the fluid reservoir which is interconnectable to thepatient. The control module includes a pumping mechanism which engagesthe tube during pumping to move fluid from the reservoir to the patient.

There are various different indicia which may be provided on the baseplate to identify a property of the reservoir. The base plate mayinclude one or more projections. The structure for identifying indiciamay include a force sensitive resistor mounted to the control module forengaging the projection on the base plate. The force sensitive resistorgenerates a signal for the processor of the control system.

Alternatively, the structure for identifying indicia may include amicroswitch mounted to the control module which engages the projectionon the base plate and sends a signal to the processor of the controlsystem.

A further alternative for the structure for identifying indicia mayinclude a slotted optical sensor and a reciprocally mounted plunger. Theslotted optical sensor and the plunger are mounted to the controlmodule. The plunger is engaged by the projection to move the projectionrelative to the optical sensor. The optical sensor generates a signalfor the processor of the control system indicative of the change inposition of the plunger.

In another alternative embodiment, the structure for identifying indiciamay include a reciprocally mounted plunger which makes or breakselectrical connection between electrical contacts during engagement bythe projection of the base plate. This electrical connection ordisconnection generates a signal for the processor.

Instead of a mechanical interaction between indicia on the base plateand the structure for identifying the indicia associated with thecontrol module, optics may be utilized wherein no contact between thecontrol module and the cassette occurs with respect to the indiciaidentification structure. In one embodiment, the control module includesa light emitter for directing light toward the base plate. The indiciaon the base plate includes an appropriately located prism arrangementfor reflecting the light back toward the control module. The structurefor identifying indicia further includes a light receiver for receivingthe light reflected from the prism arrangement associated with the baseplate and sending a signal to the processor.

Alternatively, the structure for identifying indicia may include a lightemitter for directing light toward the base plate and the base plate mayinclude a reflective patch for reflecting the light back toward thecontrol module. The structure for identifying indicia further includes alight receiver for receiving the light reflected from the reflectivepatch and sending a signal to the processor.

Other cassette identification systems are usable including thoserelating to capacitive switches, Hall effect switches, reed switches,inductive switches, piezoelectric switches, magneto-resistive switches,and other non-contact switches. Acoustic switches are also usable. Also,optical print sensors may also be utilized for reading bar codeinformation or the like printed on the cassette. Laser positioningsensors may be utilized where the height of a projection extending fromthe base plate is measured to identify the cassette.

The pump may include a display interconnected to the processor of thecontrol system. Appropriate display programs are associated with theprocessor for generating an appropriate display depending on thecassette sensed by the control module. The pump apparatus may include anaudible signal device for generating an appropriate audible signal whenthe control module has identified either a correct cassette or anincorrect cassette. Visual signals, such as a green and/or red LED, maybe provided with the pump to indicate the appropriateness of thecassette sensed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a pump apparatus according to thepresent invention, showing a self-contained fluid cassette separatedfrom the control module.

FIG. 1A is a schematic diagram of a remote reservoir adapter and remotefluid reservoir useable with the control module of FIG. 1.

FIG. 2 is a schematic diagram of the control system of the controlmodule shown in FIG. 1.

FIG. 3 is a first cassette identification system including a pluralityof force-sensitive resistors.

FIG. 4 is a second alternative cassette identification system includinga force-sensitive resistor and an elastomer.

FIG. 5 is a third alternative cassette identification system including aforce-sensitive resistor and a coil spring.

FIG. 6 is a fourth alternative cassette identification system includinga force-sensitive resistor and a flexible beam.

FIG. 7 is a fifth alternative cassette identification system including aprism arrangement.

FIG. 8 is a cross-sectional view of the identification system shown inFIG. 7 taken along lines 8--8.

FIG. 9 is a view of the light emitter of the cassette identificationsystem shown in FIGS. 7 and 8.

FIG. 10 is a sixth alternative cassette identification system includingan alternative prism arrangement.

FIG. 11 is a seventh alternative cassette identification systemincluding a reflective patch.

FIG. 12 is an eighth alternative cassette identification systemincluding a microswitch.

FIG. 13 is a ninth alternative cassette identification system includinga reciprocally mounted plunger with an electrical contact thereon.

FIG. 14 is a tenth alternative cassette identification system includinga slotted optical sensor and a reciprocally mounted plunger.

FIG. 15 is a side view of the cassette identification system shown inFIG. 14, showing three slotted optical sensors and three reciprocallymounted plungers.

FIG. 16 is a second alternative plunger arrangement to the arrangementshown in FIGS. 14 and 15.

FIG. 17 is a third alternative plunger arrangement to the arrangementshown in FIGS. 14 and 15.

FIG. 18 is a fourth alternative plunger arrangement to the arrangementshown in FIGS. 14 and 15.

FIG. 19 is a fifth alternative plunger arrangement to the arrangementshown in FIGS. 14 and 15.

FIG. 20 is a sixth alternative plunger arrangement to the arrangementshown in FIGS. 14 and 15.

FIGS. 21-29 illustrate one preferred cassette identification system.FIGS. 21-23, 26, 27 and 29 show a control module and a first cassette.FIGS. 24 and 25 show a second cassette. FIG. 28 shows a third cassette.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to systems and methods for automaticallyidentifying a cassette mounted to a control module of a fluid pumpingsystem, such as a drug infusion system. The identification system canidentify indicia on the cassette relating to the type of drug, theconcentration of the drug, the volume of the fluid reservoir, or theamount of drug pumped per activation of the pump, i.e., tube size. Suchinformation is important to safe and effective drug therapy. When theinformation is entered automatically to the control module, such as withthe indicia identifying system, a safer and more effective systemresults. There is less chance for human error, as would be the case ifsuch information were entered manually. Also, the indicia identifyingsystem can be used to prevent operation of the pump if an unauthorizedcassette is attached.

Various cassettes are provided to be identified by the control module.The control module identifies the cassettes in one of a variety ofmanners, including engagement with a projection on the cassette orsensing optical signals or the absence of optical signals due to thepresence of the cassette. Other structures and methods are provided toidentify the cassettes.

Referring now to FIG. 1, a pump apparatus or pump 20 is shown. Pump 20includes a control module 24 and a separate self-contained fluidcassette 26 which is mountable to the control module 24. Control module24 is reusable. Cassette 26 may be disposable, or in some cases reusableafter refilling. As will be discussed below in greater detail, cassette26 can be configured as a remote reservoir adapter linking a remotefluid reservoir to control module

One lock/latch mechanism for mounting cassette 26 to control 24 includesone or more hooks 45 which each engage a rod 46 mounted to controlmodule 24. Loop 47 is grasped by loop engaging device 48 to releasablyhold cassette 26 in place with hook 45 around rod 46. Other lock/latchmechanisms are anticipated for holding cassette 26 adjacent controlmodule 24 to facilitate operation.

Control module 24 includes a pumping mechanism 28 which pumps fluid fromcassette 26. Cassette 26 includes a fluid reservoir 30 with acompressible tube 32 extending therefrom. Tube 32 is interconnectable tothe patient. Cassette 26 includes a base plate or pressure plate 34having a top surface facing control module 24. Tube 32 is positionablebetween base plate 34 and pumping mechanism 28. Pumping mechanism 28includes reciprocally mounted members which engage tube 32 in aparticular manner to move fluid through tube 32. In one preferredembodiment, pumping mechanism 28 includes a reciprocally mounted inletvalve, a reciprocally mounted outlet valve, and a reciprocally mountedexpulsor. The expulsor pushes fluid through the tube 32. The inlet andoutlet valves, on opposite sides of the expulsor, open and close thetube to permit the passage of fluid through the tube 32. Pumpingmechanism 28 includes a rotatable cam shaft controlled by a motor whichmoves the inlet and outlet valves and the expulsor in the appropriatemanner. Base plate 34 and outer housing 44 cooperate to enclosereservoir 30 in FIG. 1. An example of one pumping mechanism useable inpump 20 is shown in U.S. Pat. No. 4,559,038, the disclosure of which isincorporated by reference.

Control module 24 further includes a plurality of keys 36 for providinginput structure for the operator to input information into controlmodule 24. Control module 24 also includes a display 38, such as an LCD(liquid crystal display) for displaying information to the operator. Anaudible signal device 56 may be provided to send an audible signal tothe operator indicative of various conditions of pump 20. For example, abeeper may be provided for audible signal device 56. A visual signaldevice 58 may be provided for sending a visual signal to the operatorindicative of various conditions of pump 20. For example, red and greenLED (light-emitting diodes) may be provided for visual signal device 58.

Control module 24 includes a device 42 for identifying indicia 40 oncassette 26. Various cassette identification systems are anticipatedincluding a variety of different identifying devices 42 and indicia 40.

Referring now to FIG. 2, a control system 50 for control module 24 isshown. Control system 50 includes a processor 52 electricallyinterconnected to keypad 36, display 38, pump mechanism 28, and indiciaidentifying device 42. Audible signal device 56 and visual signal device58 are interconnected to processor 52. Control system 50 furtherincludes a memory 54 for storing various programs for operating pump 20.One program to be stored in memory 54 is pump disabling program fordisabling pump mechanism 28 if an improper cassette is sensed.

FIG. 2 also shows a lock/latch sensor 60 interconnected to processor 52.Lock/latch sensor 60 senses when cassette 26 has been locked/latched tocontrol module 24 through the operator activated latch structure 45, 46,47, 48 which holds cassette 26 adjacent control module 24. FIG. 2further shows a pressure sensor 62 interconnected to processor 52.Pressure sensor 62 is utilized to sense pressure in tube 32. Pressuresensor 62 and lock/latch sensor 60 are optional with respect to cassetteidentification. However, these sensors are used to advantage duringcassette identification. These sensors can be utilized by processor 50to identify if there happens to be a malfunction of the cassetteidentification system. Processor 52 will know when cassette 26 has beenmounted to control module 24 by receipt of a lock/latch signal and anappropriate pressure signal (i.e., a pressure sensed within anacceptable operating range). At that point, processor 52 can beginlooking for an appropriate signal from the identifying device 42 foridentifying the indicia 40. If no identification signal is present,processor 52 does not permit initiation or continuation of the pumpingoperation by pump mechanism 28. Processor 52 may also send anappropriate error signal to display 38, audible signal device 56, and/orvisual signal device 58. Processor 52 checks for a cassetteidentification signal periodically or continuously. Periodic ispreferred as a manner of reducing energy consumption of pump 20.

In FIG. 2, the various sensors, switches, and other components ofcontrol system 50 are interconnected to processor 52 throughinterconnection link 64.

Referring now to FIG. 1A, a remote reservoir adapter 26a is shown whichis mountable to control module 24 in a similar manner as cassette 26.However, instead of including a self-contained fluid reservoir, adapter26a is separate from remote fluid reservoir 30a. A tube 31a links remotefluid reservoir 30a to adapter 26a. Adapter 26a includes a base plate34a with an extending base or housing 44a, hooks 45a, and a loop 47a.Housing 44a is smaller than housing 44 typically since no fluidreservoir is contained therein. Tube 32a extends from adapter 26a to belinked to the patient. As with respect to cassette 26, adapter 26aincludes identifying indicia 40a to permit identification by controlmodule 24.

In the following description of various preferred embodiments, referenceto cassette 26 is to be interpreted as either cassette 26 of FIG. 1 oradapter 26a of FIG. 1A.

Referring now to FIG. 3, a first cassette identification system 70 isshown including indicia associated with cassette 26 and indiciaidentifying structure associated with control module 24. The indicia oncassette 26 includes a projection 84 projecting upwardly from topsurface 86 of base plate 34. The indicia identifying structure oncontrol module 24 includes a plurality of force-sensitive resistors(FSRs). FSR 72 senses contact by projection 84. FSR 72 sends anappropriate signal through electrical connection 78 to processor 52 ofcontrol system 50.

As shown in FIG. 3, second FSR 74 and third FSR 76 are not engaged byany projections extending from cassette 26. Electrical connection 80 cansend an appropriate signal from a second FSR 74 indicative of acondition where no projection is sensed. Similarly, electricalconnection 82 can send a signal from third FSR 76 indicative of noprojection sensed.

Cassette identification system 70 is capable of identifying at leastthree different cassettes 26. System 70 is shown identifying a firstcassette 26. A second cassette could include a projection appropriatelypositioned to engage only second FSR 74. Similarly, a projection couldbe provided in the appropriate position to engage only third FSR 76. Inthis manner, a failure of one of the FSRs to sense the presence of aprojection does not give an erroneous signal to processor 52.

If it is a desireable to identify more than three cassettes 26 utilizingonly three FSRs, it is possible to utilize the FSRs in a manner whichidentifies up to eight different cassettes. However, it is not possibleto differentiate between cassettes if one or more of the FSRs wouldhappen to fail to identify a projection which is an engagement with therespective FSR, or if one of the projections is somehow damaged ormalformed such that no engagement occurs. When only three differentcassette sensors are provided, and only three cassettes are identifiedwith them, then only one cassette projection is sensed. If no projectionis sensed, or if more than one projection is sensed, then control module24 recognizes an improper or damaged cassette has been attached.

Referring now to FIG. 4, a second alternative cassette identificationsystem 90 is shown. Like system 70, system 90 includes FSRs. In FIG. 4,FSR 94 is shown for sensing projection 96 extending from cassette 26.Compressible elastomer 92 is positioned between base surface 91 ofcontrol module 24 and FSR 94. Elastomer 92 provides a greater range ofvariation with respect to the height of projection 96 extending fromcassette 26 relative to control module 24. Without elastomer 92, it maybe possible for projection 96 to damage FSR 94 if projection 96 happensto extend too far from cassette 26 or if projection 96 is pushed too farinto FSR 94. Similarly, if projection 96 does not extend far enough, FSR94 will not sense the presence of projection 96 if there is insufficientcontact below the threshold amount of the FSR or if there is no contactat all. Elastomer 92 extends the range of operation of FSR 94 such thatvariations in the height of projection 96 can be accommodated. Suchaccommodation is useful during manufacturing because the ranges on thepossible height of projection 96 do not have to be as narrow as theymight if no elastomer is present. Also, damage to the FSR may be avoidedif the projection is pushed into the FSR at some point during mountingor dismounting of cassette 26.

Referring now to FIG. 5, a third alternative cassette identificationsystem 100 is shown. Instead of an elastomer 92 in system 90, system 100includes a coil spring 104 which biases FSR 102 away from base surface101 of control module 24. FSR 102 senses the presence of projection 106extending from cassette 26. Spring 104 provides for an extended range inthe height of projection 106 relative to control module 24. It will beappreciated that other types of springs, such as wavy, belleville andothers could be used instead of coil spring 104.

Referring now to FIG. 6, a fourth alternative cassette identificationsystem 110 is shown. Instead of an elastomer 92 as in system 90, or aspring 104 as in system 100, system 110 includes a flexible beam 114extending from top surface 111 of control module 24. Flexible beam 114positions FSR 112 at a spaced apart distance from top surface 111. FSR112 senses the presence of projection 116. Flexible beam 114accommodates variations in the extension of projection 116 relative tocontrol module 24.

Referring now to FIGS. 7-9, a fifth alternative cassette identificationsystem 130 is shown. Cassette 26 includes a prism arrangement 140 forreflecting light from control module 24 in an appropriate manner backtoward control module 24 to identify cassette 26. Prism arrangement 140includes a top surface 142, a first prism surface 144, a second prismsurface 146, and a top surface 148. Base plate 34 is constructed toinclude prism arrangement 140 with the top surfaces 146, 148 forming atop surface portion of base plate 34 and surfaces 144, 146 forming abottom surface portion of base plate 34.

Light emitter 132 emits light represented by arrows 133 which entersprism arrangement 140 and is reflected back toward control module 24. Asshown in FIG. 7, prism arrangement 140 is reflecting light from emitter132 to receiver 134. Receiver 134 sends an appropriate signal toprocessor 52 indicative of the presence of prism arrangement 140reflecting light to receiver 134. Base plate 34 of cassette 26 is madefrom a material which permits the passage of light from emitter 132 tobe reflected internally at surfaces 144 and 146. In one preferredembodiment, base plate 34 is made from polycarbonate which has an indexof refraction of about 1.6 relative to air. Angles of 45 degreesrelative to the direction of light passage are utilized for surfaces 144and 146 in order to obtain sufficient internal reflection to havereceiver 134 sense light being emitted from emitter 132.

To indicate the presence of a second cassette different from cassette26, prism arrangement 140 is provided with a different configuration.Receiver 136 is utilized instead of receiver 134. In order to havereceiver 136 receive light from emitter 132, surface 146 is movedadjacent (below in FIG. 7) receiver 136. Surface 144 would remain in thesame location that is depicted in FIG. 7. Receiver 136 would send anappropriate signal to processor 52 indicative of the presence of prismarrangement 140 reflecting light to receiver 136.

To indicate the presence of a third cassette, receiver 138 is utilized.In order to have receiver 138 sense light from emitter 132, surface 144is positioned in a reverse direction to reflect light from emitter 132toward receiver 138. Surface 146 is appropriately positioned beneathreceiver 138. In this manner, three different cassettes can be sensed bycontrol module 24.

As shown in FIG. 7, top surface 142 is configured as a lens surface forcolumnating the light from emitter 132. As shown in FIGS. 7 and 8, topsurface 148 is also configured as a lens for focusing the light passingthrough base plate 34 toward receiver 134.

Receivers 134, 136, 138 can be any of a variety of light receivers whichgenerate a signal when light is present. Receivers 134, 136, 138 may bephototransistors, photodiodes, or photodarlingtons.

Referring to FIG. 9, an example of an emitter 132 is shown in greaterdetail. Emitter 132 may be an infrared emitting diode. An epoxy coating154 encloses chip 156 which emits the infrared light. Extending fromemitter 132 are two leads 150, 152 to connect to processor 52.

In cassette identification system 130, a comparitor circuit is usefulfor comparing the signals from all three receivers 134, 136, 138. It ispreferred that the three receivers, 134, 136, 138 each generate asignal, with one signal being strong and two being weak. The comparitorcircuit identifies the receiver with the stronger signal as being thereceiver positioned in the appropriate manner relative to the prismarrangement 140 for identification of the cassette. The two weakersignals indicate that some light is reaching the receivers, but thatlight is not intended to cause those receivers to indicate the presenceof the prism arrangement 140. The light that is being received byreceivers 136, 138 which generates the weaker signals could come fromemitter 132. Also, the light could come from external of pump 20.

One preferred cassette identification system 130 may include amodulating signal with respect to emitter 132. The light wouldpreferably flash at a frequency not commonly found in the environmentswhere pump 20 is to be used. This would increase the accuracy ofcassette identification system 130. The modulating signal set at theuncommon frequency would help reduce inaccurate results caused bysunlight, room lighting, or other lighting devices which produce lightwhich could hit pump 20, possibly causing an inaccurate reading of thecassette identification system.

Referring now to FIG. 10, a sixth alternative cassette identificationsystem 160 is shogun. Control module 24 in FIG. 10 is similarly arrangedas control module 24 of FIGS. 7 and 8. An emitter 162 is provided fordirecting light toward cassette 26. Cassette 26 includes structure forreflecting the light back toward control module 24. In particular, baseplate 34 of cassette 26 includes a prism arrangement 170 which has aplurality of indentations. A first indentation 171 includes a firstprism surface 174. A second indentation 175 provides a second prismsurface 176. As shown in FIG. 10, light, represented by arrow 177, isemitted by emitter 162, passes through top surface 172 of base plate 34,and is reflected by first prism surface 174 toward second prism surface176. Second prism surface 176 reflects the light back toward receiver164.

As shown in FIG. 10, prism arrangement 170 is not directing light towardeither second receiver 166 or third receiver 168. These receivers areutilized to identify different cassettes from cassette 26. A differentprism arrangement 170 would be provided to reflect light from emitter162 to receiver 166. In particular, indentation 175 and second prismsurface 176 would be positioned beneath second receiver 166. Similarly,prism arrangement 170 would be modified in order to direct light fromemitter 162 to third receiver 168 in order to identify a third cassette.In particular, indentation 171 and indentation 175 would be provided ina manner that first prism surface 174 and second prism surface 174 woulddirect light from emitter 162 toward receiver 168.

In cassette identification system 160, a comparitor circuit is usefulfor comparing the signals from all of the receivers 164, 166, 168. Thisidentifies the stronger signal which is associated with the prismarrangement 170 directing light toward a particular receiver forcassette identification.

In an alternative arrangement (not shown) to the systems 130 and 160 ofFIGS. 7-10, three emitters and one receiver could be provided. In thatcase, the emitters are switched on and off at different times and acomparitor circuit compares the signal received at the receiver fromeach emitter to identify which cassette 26 is being identified.

Referring now to FIG. 11, a seventh alternative cassette identificationsystem 180 is shown. Instead of a separate emitter and receivers, system180 includes three components 182, 184, and 186, which each function asan emitter of light and a receiver of light. Cassette 26 is providedwith a reflective patch 188 for reflecting light back toward controlmodule 24. Reflective patch 188 is appropriately positioned to reflectlight back at one of the emitter/receiver components 182, 184, 186. Inthis case, patch 188 is below emitter/receiver component 182. The system180 of FIG. 11 requires that reflective patch 188 be appropriatelypositioned during manufacturing. Base plate 34 reflects light, but in adifferent amount from reflector 188. It is not necessary that reflector188 reflect more light than base plate 34.

An advantage of system 130 shown in FIGS. 7-9, and system 160 shown inFIG. 10 is that base plate 34 is molded with the appropriateconfiguration concerning the prism arrangement. No additional steps ofplacing a component or part on cassette 26 is needed with respect tosystems 130, 160.

In cassette identification system 180, a comparitor circuit is usefulfor comparing the signals from the receivers of all three components182, 184, 186. This identifies the stronger (or weaker) signal which isassociated with the component positioned adjacent reflective patch 188.

Referring now to FIG. 12, an eighth cassette identification system 200is shown. A microswitch 202 is activated when projection 216 movesplunger 204. Plunger 204 is positioned in opening 205 through chassis207 of control module 24. A rubber boot 206 closes opening 205 fromcontaminants. Spring 208 biases plunger 204 away from microswitch 202.Spring 208 is positioned between spring retainer 210 mounted to chassis207 and flange 212 of plunger 204. A seal 214 seals opening 205 fromcontaminants entering an interior of control module 206. Seal 214 andboot 206 serve similar functions in keeping contaminants out of controlmodule 26. As such, it is anticipated that only one is needed.

Microswitch 202 is preferably adjustably mounted to board 209. Board 209is mounted to chassis 207. Board 209 is useful for mounting other pumpcircuit components. An adjustable mounting permits adjustability ofswitch 202 such that the anticipated range of motion of plunger 202,including the various tolerances of projection 216, can be accommodatedfor during assembly and use such that consistent operation is achieved.

Referring now to FIG. 13, a ninth alternative cassette identificationsystem 260 is shown. A plunger 262 is reciprocally mounted in aperture263 in chassis 261 of control module 24. Plunger 262 is spring biased byspring 266 toward the position shown in FIG. 13. Seal 265 seals controlmodule 24 from contaminants that come in contact with control module 24.Seal 265 also biases plunger 262 to the position shown in FIG. 13.Spring 266 is positioned between flange end 264 and spring retainer 274.When projection 280 engages flange cap 268 such that plunger 262 ismoved upwardly, electrical contact is broken between upper contact 276and a lower contact 275 located on spring retainer 274. Alternatively,electrical contact can be made when plunger 262 is moved upwardly towarda contact positioned above upper contact 276. Cap 268 is pressed intofoam seal 270 in this position. An insulator 278 is press fit on an endof plunger 262. Insulator 278 is positioned between plunger 262 andupper contact 276 to insulate plunger 262.

Referring now to FIGS. 14 and 15, a tenth alternative cassetteidentification system 320 is shown. The cassette identification system320 includes a board 322 positioned in an interior of control module 24.Mounted to board 322 are three slotted optical sensors 324, 350, 354.The optical sensors 324, 350, 354 may be soldered to board 322 at pins329. The optical sensors are electrically connected to the processor ofthe control module. Board 322 is used for mounting various other circuitcomponents of pump 20. Board is mounted to chassis 341 of control module24 with at least one bolt 356 and a spacer 357. Pins (not shown)inserted into board 322 and chassis 341 may be used to achieve greateraccuracy in mounting board 322 to chassis 341 during manufacturing.

In FIGS. 14 and 15, each optical sensor 324, 350, 354 is identical.Sensor 324 includes a light emitter on one side of slot 325 and areceiver on the opposite side of slot 325. Sensor 324 sends anappropriate signal to the processor of the control module indicative ofwhether, or to what degree, light from the emitter is being received bythe receiver of sensor 324.

In system 320, three plungers 326, 352, 358 are reciprocally mounted tochassis 341. Plungers 326, 352, 358 are shown in a first position inFIGS. 14 and 15. In the first position, the path between the emitter andthe receiver of each optical sensor is unobstructed. In some cases, theend of the plunger may be partially received by the sensor in the firstposition. In that case, the light path between the emitter and thereceiver in the first position is less obstructed than in a secondposition. In one preferred embodiment, a higher voltage signal is sentto the processor of the control module when the plunger is in the fistposition than when the plunger is in the second position.

In the system of FIGS. 14 and 15, slot 325 of optical sensor 324receives an end 327 of plunger 326 when plunger 326 is moved upwardly toa second position. In the second position, the path between the emitterand the receiver is at least partially obstructed (or more obstructedthan the first position). In one preferred embodiment, a lower voltagesignal is sent to the processor of the control module than when theplunger is in the first position. Alternatively, the light path canbecome less obstructed when plunger 326 is moved by the projection tothe second position.

Extending from the base plate 348 of cassette 24 is a projection 346which engages an end 328 of one of the plunger 326 to move that plungerfrom the first position to the second position when cassette 26 ismounted to control module 24. An appropriately positioned projection 346can be used to identify that cassette from one or more other cassetteswhich are not provided with a projection. The processor of controlmodule 24 looks for the optical sensor sending the lower voltage signalindicative of the presence of a particular plunger in the secondposition. Preferably, although not required, control module 24 looks fora single projection. Identification of one, two or three projections maybe used to identify up to eight cassettes, if desired.

Plunger 326 is spring biased away from the respective optical sensor 324by spring 332 and seal 340. Spring 332 is positioned between springretainer 334 mounted to chassis 341. A flange 330 is provided on plunger326 to trap spring 332 between spring retainer 334 and flange 330.Chassis 341 further includes a recess 342 for receipt of seal 340. Seal340 may be a foam seal for preventing moisture from entering the insideof the control module 24.

Plunger 326 can be made from round stock. End 327 is flattened to anappropriate width to be received by slot 325 of slotted optical sensor324. A C-clip 359 limits each of the plungers 326 from moving too faraway from the optical sensors 324. A groove or notch may be provided onplunger 326 to hold C-clip from axial movement along the plunger.

Referring to FIG. 16, a second alternative plunger arrangement is shown.Spring retainer 400 is provided with a slot 402 instead of an opening asin spring retainer 334. Plunger 404 is provided with a notch 406. Thelength of notch 406 along the longitudinal axis 408 of plunger 404defines a range of possible movements of plunger 404.

Referring to FIG. 17, a third alternative plunger arrangement is shown.Instead of a C-clip 359, a pin 410 is inserted through plunger 412. Pin410 engages spring retainer 414 to limit movement of plunger 412.

Referring to FIG. 18, a fourth alternative plunger arrangement is shown.A flange 430 is provided on plunger 426 to trap spring 432 betweenspring retainer 434 and flange 430. A stop surface 436 on plunger 426engages stop surface 438 on chassis 424 to limit the distance plunger426 can be biased away from the optical sensor. Chassis 424 furtherincludes a recess 442 permitting receipt of seal 440 when plunger 426 ismoved toward the optical sensor. A groove 444 is provided on plunger 426to hold seal 440 in an appropriate position.

Referring now to FIG. 19, a fifth alternative plunger arrangement isshown. Plunger 452 is mounted to chassis 450 wherein a resilient siliconseal 458 seals the opening in chassis 450 for plunger 452. Seal 458 fitsin recess 454. A metal ring 466 helps hold first end 462 of seal 458 inthe position shown. Second end 464 of seal 458 holds plunger 456 inrecess 460. As plunger 456 is moved up and down during use, such as insystem 220 as shown in FIGS. 14 and 15, second end 464 moves withplunger, thereby effectively sealing the opening in the chassis.

Referring now to FIG. 20, a sixth alternative plunger arrangement isshown. Instead of seal 458 of FIG. 19, seal 474 is provided for sealingthe opening in the chassis for plunger 478. First end 475 of seal 474engages the chassis. A second end 476 engages a recess 480 in plunger478. Second end 476 of seal 474 moves with plunger 478 as plunger 478moves up and down during attachment and detachment of cassette 26.

FIGS. 3-20 illustrate various cassette identification systems involvingeither contact or non-contact between cassette 26 and control module 24.Some alternative non-contact cassette identification systems includethose utilizing a magneto-resistive switch as part of the cassetteidentification device 42, and a magnet associated with cassette 26 asthe indicia 40. The magneto-resistive switch sends a signal to theprocessor 52 that the resistivity induced in a current carryingconductor or semiconductor is changed by the application of the magneticfield from the magnet on cassette 26.

The cassette identifying device 42 could instead include a Hall effectsensor, with indicia 40 including a magnet. A Hall effect switch is amagnetically activated switch that uses a Hall generator, a triggercircuit, and a transistor amplifier on a silicon chip. A furtheralternative may include a cassette identifying device having a reedswitch, with indicia 40 including a magnet. A reed switch typically hascontacts mounted on ferromagnetic reads sealed in a glass tube designedfor actuation by application of the magnetic field of the magnet.

Another alternative indicia identifying device 42 may include apiezoelectric switch or a capacitive switch. Further alternativeembodiments may include an acoustical emitter/detector for indiciaidentifying device 42. Additional embodiments of indicia identifyingdevice 42 include bar code readers or other text or printed markingreaders which can read printed material on cassette 26. Laserpositioning sensors may be utilized where the height of a projectionextending from the base plate is measured to identify the cassette.

While the systems shown in FIGS. 3-20 identify cassettes 26 byidentifying a single indicia 40 on each cassette, it is to be understoodthat the identification system could look for two indicia, such as twoprojections, for each cassette. A redundant system could still beprovided in that case since the control module would request that twosignals be received. Less than two or more than two would indicate anerror condition. Moreover, the invention is not to be limited to threesensors. More than three, or less than three, are possible whether thesystems sense the presence of one indicia, the absence of one indicia,or variations in the number of indicia sensed, such as zero, one, two,three, etc. corresponding to the number of sensors provided and thepossible combinations thereof.

Referring now to FIGS. 21-29, a preferred cassette identification systemis shown. FIGS. 21-23, 26, 27 and 29 show a preferred control module550, a preferred cassette sensing mechanism 542, and a first preferredcassette 526. FIG. 21 shows first cassette 526 assembled and mounted tocontrol module 550. FIGS. 26, 27 and 29 show various side and top viewsof a base plate 530 of cassette 526, and a perspective view of a base532 of cassette 526. FIG. 22 shows only chassis 552 with the variousplungers mounted thereto. FIG. 23 is an enlarged view of a portion ofchassis 552 with a slotted optical sensor 676 shown in its relativeposition to plunger 666. FIGS. 24 and 25 show a second cassette 626 inside and top views, respectively. FIG. 28 shows a third cassetteportion, base plate 730, useable with base 532 of FIG. 29 to form thirdcassette 726 in a similar manner as first cassette 526. The second andthird preferred cassettes 626 and 726 are also part of the preferredcassette identification system. Cassette sensing mechanism 542 candistinguish between cassettes 526, 626, 726. For example, first cassette526 can have a first pumping volume per activation, i.e., 50 μl. Secondcassette 626 can have a second pumping volume per activation, differentfrom the first pumping volume, i.e., 100 μl. It is critical for controlmodule 550 to know how much fluid is pumped per activation of thepumping mechanism to deliver the desired drug therapy. In an improperdrug therapy, either too much or too little drug can be harmful, and insome cases, fatal.

While variations of cassette identification systems have been shown inFIGS. 1-20, and described above, the cassette identification system ofFIGS. 21-29 is preferred. As shown in FIG. 21, first cassette 526includes base plate 530 and base 532 mounted thereto. Base plate 530 isshown in greater detail in FIGS. 26 and 27. Base 532 is shown in greaterdetail in FIG. 29. Base plate 530 is adhesively attachable to base 532.Alternatively, a snap arrangement can be provided. In a furtheralternative, a snap arrangement and adhesive can be utilized. In afurther alternative, base plate 530 and base 532 can be integrallyformed as a single unit, such as by molding in the case of plastics.

Control module 550 includes a chassis 552 and an outer housing 554. Aseal 556 seals between chassis 552 and housing 554. A component board558 is mounted to chassis 552 via screws 560, spacers 562, and alignmentpins 564. A first plunger 566 is reciprocally mounted to chassis 552.Second plunger 666 and third plunger 766 are also reciprocally mountedto chassis 552. Plungers 566, 666, 766 are similarly configured andoperated. FIG. 23 shows second plunger 666 in greater detail. A seal 668seals an end of second plunger 666. A spring 670 biases second plunger666 to the position shown in FIGS. 21-23. A bezel 672 traps spring 670in position as shown. A flange 674 limits second plunger 666 from beingpulled downwardly out of the position shown in FIGS. 21-23. Duringoperation, a projection extending from the cassette engages end 667 andcauses upward movement of second plunger 666 such that end 678 of secondplunger 666 moves into a new position relative to slotted optical sensor676, which causes a signal to be sent to the processor of control module550 that a projection has been sensed.

First plunger 566 and third plunger 766 are provided for sensingadditional projections. In particular, first plunger 566 engagesprojection 534 extending from the main surface 536 of base plate 530 offirst cassette 526. Second plunger 666 engages second projection 634extending from main surface 636 of base plate 630 of second cassette626. Third plunger 766 engages projection 734 extending from base plate730 of third cassette 726. In this manner, control module 550 canidentify at least three different cassettes 526, 626, 726.

Referring in particular to FIGS. 21, 26, 27 and 29, base plate 530, andbase 532 are shown. Extending from main surface 536 are a pair of hooks538 adjacent to a first transverse end 540. A loop 542 extends from themain surface 536 adjacent to a second transverse end 544. A plurality oftube guide pairs 545, 546, 547, 548 extend from main surface 536 and arespaced apart to receive a flexible tube, in a general direction parallelto first and second longitudinal sides 541, 543 of main surface 536. InFIG. 26, background portions have been removed behind thecross-sectional portion for clarity. In FIG. 27, a tube 549 is shown indashed lines.

Referring now to FIGS. 24 and 25, base plate 630, and base 632 are shownin greater detail. Extending from main surface 636 are a pair of hooks638 adjacent to a first transverse end 640. A loop 642 extends from mainsurface 636 adjacent to a second transverse end 644. A plurality of tubeguide pairs 645, 646, 647, 648 extend from main surface 636 and arespaced apart to receive a flexible tube, in a general direction parallelto first and second longitudinal sides 641, 643 of second cassette 666.In FIG. 25, a tube 649 is shown in dashed lines.

As shown by a comparison of FIGS. 24 and 25 with FIGS. 26 and 27,projection 534 is in a different relative location to projection 634 ina direction parallel to longitudinal sides 641, 643. It should also benoted that FIGS. 24 and 25 illustrate the integral construction betweenbase plate 630 and base 632. Cassette 626 also includes features formore accurate centering of tube 649 which is larger than tube 549, suchas the V-shaped passages provided in connection with guide pairs 645,646, 647, 648.

Also, cassette 626 includes clip features for releasably gripping tube649 to provide a mechanical hold down during adhesive attachment of tube649 to cassette 646. In particular, first clip 650 and second clip 652provide hold down of tube 649 to cassette 626. First clip 650 and secondclip 652 hold the tube in place during assembly, allowing the adhesiveto set up without the need for special clamps or external fixtures.

Referring now to FIG. 28, third cassette 726 is shown. With respect toFIG. 28, a base plate 730 is illustrated. Base 532 shown in FIG. 29 isuseable with base plate 730 shown in FIG. 28. Projection 734 is in adifferent relative location on base plate 730 than projection 534 ofbase plate 530 and projection 634 of base plate 630. Projection 734 canbe indicative of a different cassette property to differentiate cassette726 from cassettes 626, 526. For example, cassette 726 may include anindication that an air filter is present to identify to the controlmodule when the cassette is utilized with a reservoir including anin-line air filter.

The cassette identification system of FIGS. 21-29 incorporates featuresof embodiments described in various of FIGS. 1, 1A, 2, 14, 15, 18, and20, for example. The system of FIGS. 21-29 may be advantageous overmechanical switches, such as microswitches, since little or no emphasisneed be placed on overtravel, individual adjustment, arcing problems,and mechanical wearing of the switch. Inductive, magnetic, or reflectivesystems may require the placement of an additional element on thecassette during manufacture. A projection as in FIGS. 21-29 can beintegrally formed on the cassette during manufacture, possiblysimplifying manufacture. Force sensitive resistors may be prone toproblems due to typical range of necessary movement and the typicaltolerances of the disposable cassettes. Also, the plastics associatedwith the FSR or its spring may be subject to creep problems over time,possibly further complicating the range of motion and tolerance problem.Make or break switches where the contacts are mounted to a moveableplunger, for example, may be prone to failure due to the failure of thecontact points, such as due to pitting or corrosion, or due to thecomponents getting stuck open or closed.

Reciprocally mounted plungers and slotted optical sensors are useful tosolve some of the above possible problems and other problems withcassette identification systems. However, it is to appreciated that insome instances the use of microswitches, FSR's, inductive switches,magnetic switches, reflective elements, moving contacts, or othersystems noted above may be desireable.

While the present invention has been described in connection with thepreferred embodiments thereof, it will be understood many modificationswill be readily apparent to those skilled in the art, and thisapplication is intended to cover any adaptations or variations thereof.It is intended this invention be limited only by the claims andequivalents thereof.

What is claimed is:
 1. A base plate for use with a control module havinga projection sensing member comprising:a body having a main surfacefacing in a first direction and including first and second longitudinalsides, and first and second transverse ends, the main surface configuredto receive a flexible tube in a direction generally parallel to thefirst and second longitudinal sides; a pair of hooks extending from themain surface adjacent to the first transverse end; a loop extending fromthe main surface adjacent to the second transverse end; and a projectionextending from the main surface positioned to engage the projectionsensing member of the control module.
 2. The base plate of claim 1,further comprising a tube guide pair extending from the main surface andspaced apart to receive the flexible tube.
 3. The base plate of claim 1,further comprising a flexible tube mounted to the body.